We propose to establish a facility for determining the amino acid sequence of proteins which will be shared by a core user group of five investigators, a secondary user group of six investigators and a potential user group. Major pieces of equipment will include a Beckman 890C Sequencer, a high sensitivity, high capacity amino acid analyzer, and a high performance liquid chromatograph. These instruments will be operated by the facility staff. Th staff will also maintain an extensive assortment of equipment necessary for the separation and purification of peptides, and this equipment will be operated by the users. The structures of a wide variety of proteins will be studied, including ten enzymes, four classes of electron carriers, lectins, membrane glycoproteins, and a copper-binding myeloma protein. Protein-protein interaction involving electron transfer and involving alpha 2-macroglobulin inactivation of plasmin will be studied by cross-linking and sequencing of the interface regions.